title: CXCL12 induces hepatic stellate cell contraction through a calcium-independent pathway.
abstract: Liver fibrosis, with subsequent development of cirrhosis and ultimately portal hypertension, results in the death of patients with end-stage liver disease if liver transplantation is not performed. Hepatic stellate cells (HSCs), central mediators of liver fibrosis, resemble tissue pericytes and regulate intrahepatic blood flow by modulating pericapillary resistance. Therefore, HSCs can contribute to portal hypertension in patients with chronic liver disease (CLD). We have previously demonstrated that activated HSCs express functional chemokine receptor, CXCR4, and that receptor engagement by its ligand, CXCL12, which is increased in patients with CLD, leads to further stellate cell activation in a CXCR4-specific manner. We therefore hypothesized that CXCL12 promotes HSC contraction in a CXCR4-dependent manner. Stimulation of HSCs on collagen gel lattices with CXCL12 led to gel contraction and myosin light chain (MLC) phosphorylation, which was blocked by addition of AMD3100, a CXCR4 small molecule inhibitor. These effects were further mediated by the Rho kinase pathway since both Rho kinase knockdown or Y-27632, a Rho kinase inhibitor, blocked CXCL12 induced phosphorylation of MLC and gel contraction. BAPTA-AM, a calcium chelator, had no effect, indicating that this pathway is calcium sensitive but not calcium dependent. In conclusion, CXCL12 promotes stellate cell contractility in a predominantly calcium-independent fashion. Our data demonstrates a novel role of CXCL12 in stellate cell contraction and the availability of small molecule inhibitors of the CXCL12/CXCR4 axis justifies further investigation into its potential as therapeutic target for portal hypertension.
authors.affiliation: Icahn School of Medicine at Mount Sinai, 1425 Madison Ave., Rm. 11-70, Box 1123, New York, NY 10029. meena.bansal@mssm.edu.
authors.forename: Yedidya
authors.initials: Y
authors.lastname: Saiman
authors.forename: Ritu
authors.initials: R
authors.lastname: Agarwal
authors.forename: DaShawn A
authors.initials: DA
authors.lastname: Hickman
authors.forename: Michel
authors.initials: M
authors.lastname: Fausther
authors.forename: Ahmed
authors.initials: A
authors.lastname: El-Shamy
authors.forename: Jonathan A
authors.initials: JA
authors.lastname: Dranoff
authors.forename: Scott L
authors.initials: SL
authors.lastname: Friedman
authors.forename: Meena B
authors.initials: MB
authors.lastname: Bansal
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D048430:Cell Shape / Q000187:drug effects*; D002614:Chelating Agents / Q000494:pharmacology; D054377:Chemokine CXCL12 / Q000494:pharmacology*; D003094:Collagen / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005782:Gels; D055166:Hepatic Stellate Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D051379:Mice; D018994:Myosin Light Chains / Q000378:metabolism; D010641:Phenotype; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D034622:RNA Interference; D019718:Receptors, CXCR4 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D014162:Transfection; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism
chemical_list: C558396:Acta2 protein, mouse; D000199:Actins; C515255:CXCL12 protein, human; C527276:CXCR4 protein, human; C514936:CXCR4 protein, mouse; D002614:Chelating Agents; D054377:Chemokine CXCL12; C515256:Cxcl12 protein, mouse; D005782:Gels; D018994:Myosin Light Chains; D047428:Protein Kinase Inhibitors; D019718:Receptors, CXCR4; D011994:Recombinant Proteins; D003094:Collagen; C515854:Rock1 protein, mouse; D054460:rho-Associated Kinases; D002118:Calcium
keywords: CXCR4; liver fibrosis; portal hypertension